22 



THE 



PART I 



to large irregular areas of a soft cuticle, as in the 

 Annelids and in the trunk segments of Apus, are 

 attached to definite firm points. (Z>.) There are thick- 

 ened strips to resist the longitudinal pulls of muscles, 

 as along the shafts of the limbs, where, but for such 



e*-. 



FIG. 4. Anterior (concave) aspect of a trunk limb of a large specimen of Apus 

 cancriformis. The shading shows the commencement of the thickening of the 

 cuticle, the white parts being thin and transparent. The musculature at the base 

 of the limb is slightly indicated. Lettering the same as in Fig. 6, p. 32. 



bands, the cuticle of the limb would be drawn into 

 folds (Fig. 4). 



(3) There are thickenings for the formation of claws 

 and teeth at the tips or edges of limbs, and of thorns 



